Kobresia pygmaea meadows as disclimax communities in the same geographic and climatic environments in Qinghai–Tibet Plateau, China

Abstract

Kobresia meadows are the main pastures for animal husbandry on the Qinghai–Tibet Plateau, and may represent alternative steady states associated with different grazing intensities. The ability of other plant communities to succeed these meadows remains unclear. In this study, the historical data of plant communities were analyzed in terms of the soil profile, and the present characteristics were identified by investigating their plant communities. Four types of steady states were identified, corresponding to grazing intensities of >11, 8–11, 5.5–8, and < 5.5 sheep/ha. Drought alpine swamp meadows and shrub meadows could succeed to K. pygmaea meadows and K. humilis meadows under overgrazing, and their total biomass and edible biomass (estimated by Gramineae and Cyperaceae) decreased with increasing grazing intensity. The regime shift of the states occurred at a grazing intensity of 8–11 sheep/ha. This value thus represented the threshold of significant change in the production and ecological service function in the Kobresia meadow succession process. In general, increasing grazing intensities can adversely affect the service ability of meadows for livestock production and ecosystem stabilization. This study revealed the potential degraded succession process of the alpine Kobresia meadow and the succession direction in the restoration process of degraded meadows. Additionally, this study provided a theoretical basis for evaluating the fitness between the livestock bearing capacity and carrying capacity in steady states and academic reference for policy setting pertaining to the utilization of Kobresia meadows in a sustainable development framework.